Serverside validation for m.room.power_levels event. (SYN-120)

[matrixbot]

Serverside validation for m.room.power_levels events as they an unholy mix of integers and strings in some channels

(Imported from https://matrix.org/jira/browse/SYN-120)

(Reported by @ara4n)

[matrixbot]

Jira watchers: @NegativeMjark @ara4n

[matrixbot]

Taken from "Matrix Internal".

{
  "@​LeoNerd:matrix.org": 100,
  "@​Mjark:matrix.org": "100",
  "@​dave:matrix.org": "100",
  "@​erikj:jki.re": "100",
  "@​kegan:matrix.org": "100",
  "@​matthew:matrix.org": "100",
  "@​neb:matrix.org": 100,
  "@​oddvar:matrix.org": 99,
  "default": 0
}

Possibly due differences between Leo's perl client and the web client? We should probably have better C2S and S2S validation for the event content.

-- @NegativeMjark

[Half-Shot]

Can we shoot this in the head for the next version bump?

[erdnaxeli]

Having a power level being a string instead of an int makes the /upgraderoom code crash:

2020-05-28 15:36:01,839 - synapse.http.server - 110 - ERROR - POST-101101 - Failed handle request via 'Roo
mUpgradeRestServlet': <XForwardedForRequest at 0x7fe1efbe6978 method='POST' uri='/_matrix/client/r0/rooms/!gRrCzddQslIHoyrgwJ%3Amatrix.org/upgrade' clientproto='HTTP/1.1' site=8008>
Traceback (most recent call last):
  File "/opt/venvs/matrix-synapse/lib/python3.7/site-packages/twisted/internet/defer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
StopIteration: {('m.room.power_levels', ''): '$159067103139tJGGs:cervoi.se', ('m.room.topic', ''): '$15005781984112702txYYW:matrix.org', ('m.room.history_visibility', ''): '$1500301245224694DtwYG:matrix.org', ('m.room.avatar', ''): '$15005773424098264pQgLH:matrix.org', ('m.room.guest_access', ''): '$1500301169223450JVurV:matrix.org', ('m.room.name', ''): '$15005781124111252eKoVg:matrix.org', ('m.room.join_rules', ''): '$1500301245224695ZMvZw:matrix.org'}

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/venvs/matrix-synapse/lib/python3.7/site-packages/twisted/internet/defer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
StopIteration: {('m.room.power_levels', ''): '$159067103139tJGGs:cervoi.se', ('m.room.topic', ''): '$15005781984112702txYYW:matrix.org', ('m.room.history_visibility', ''): '$1500301245224694DtwYG:matrix.org', ('m.room.avatar', ''): '$15005773424098264pQgLH:matrix.org', ('m.room.guest_access', ''): '$1500301169223450JVurV:matrix.org', ('m.room.name', ''): '$15005781124111252eKoVg:matrix.org', ('m.room.join_rules', ''): '$1500301245224695ZMvZw:matrix.org'}

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/venvs/matrix-synapse/lib/python3.7/site-packages/synapse/http/server.py", line 78, in wrapped_request_handler
    await h(self, request)
  File "/opt/venvs/matrix-synapse/lib/python3.7/site-packages/synapse/http/server.py", line 331, in _async_render
    callback_return = await callback_return
  File "/opt/venvs/matrix-synapse/lib/python3.7/site-packages/synapse/rest/client/v2_alpha/room_upgrade_rest_servlet.py", line 76, in on_POST
    requester, room_id, new_version
  File "/opt/venvs/matrix-synapse/lib/python3.7/site-packages/synapse/handlers/room.py", line 146, in upgrade_room
    new_version,  # args for _upgrade_room
  File "/opt/venvs/matrix-synapse/lib/python3.7/site-packages/twisted/internet/defer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
  File "/opt/venvs/matrix-synapse/lib/python3.7/site-packages/synapse/handlers/room.py", line 195, in _upgrade_room
    tombstone_event_id=tombstone_event.event_id,
  File "/opt/venvs/matrix-synapse/lib/python3.7/site-packages/synapse/handlers/room.py", line 378, in clone_existing_room
    initial_state[(EventTypes.PowerLevels, "")]
  File "/opt/venvs/matrix-synapse/lib/python3.7/site-packages/synapse/events/utils.py", line 445, in copy_power_levels_contents
    "Invalid power_levels value for %s.%s: %r" % (k, k1, v1)
TypeError: Invalid power_levels value for users.@fwhcat:mux.re: '100'

[melroy89]

Indeed same error:

2020-12-24 22:21:51,461 - synapse.http.server - 79 - ERROR - POST-91167 - Failed handle request via 'RoomUpgradeRestServlet': <XForwardedForRequest at 0x7f823f0dda60 method='POST' uri='/_matrix/client/r0/rooms/!secret_room_id%3Amatrix.org/upgrade' clientproto='HTTP/1.0' site=8008>
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/synapse/http/server.py", line 224, in _async_render_wrapper
    callback_return = await self._async_render(request)
  File "/usr/local/lib/python3.8/site-packages/synapse/http/server.py", line 400, in _async_render
    callback_return = await raw_callback_return
  File "/usr/local/lib/python3.8/site-packages/synapse/rest/client/v2_alpha/room_upgrade_rest_servlet.py", line 76, in on_POST
    new_room_id = await self._room_creation_handler.upgrade_room(
  File "/usr/local/lib/python3.8/site-packages/synapse/handlers/room.py", line 165, in upgrade_room
    ret = await self._upgrade_response_cache.wrap(
  File "/usr/local/lib/python3.8/site-packages/twisted/internet/defer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
  File "/usr/local/lib/python3.8/site-packages/synapse/handlers/room.py", line 223, in _upgrade_room
    await self.clone_existing_room(
  File "/usr/local/lib/python3.8/site-packages/synapse/handlers/room.py", line 411, in clone_existing_room
    ] = power_levels = copy_power_levels_contents(
  File "/usr/local/lib/python3.8/site-packages/synapse/events/utils.py", line 446, in copy_power_levels_contents
    raise TypeError(
TypeError: Invalid power_levels value for users.@purple_azurite:matrix.org: '0'

Could be fixed easily by the built-in Python: int()